Ionic tube circuits



Aug 10, 1943- A. PERLMANN 2,326,677

IONIKC TUBE CIRCUITS Filed Oct. 22, 1940 2 Sheets-Sheet 1 j v @w vPatented Aug. 10, 1.943

Application October 2,2, 1940, Serial No. 362,300 In Great Britain October 23, 1939 Claims.

This invention relates to improvements in ionic tubes.

A tube which can be used in carrying out the present invention consists ybrieily of an electron emitting cathode, an anode, and situated between the lcathode and anode a cylindrical collecting electrode, these three members being arranged within an evacuated envelope, which henceforth will be called a tube. The tube is filled to a low pressure with an inert gas such as helium, argon, neon or mercury vapour and when a potential difference is applied across the cathode-anode,

converting direct current to alternating current;

and

Figure 7 illustrates a method of controlling the i strength of a direct current.

'the electrons emitted from the cathode cause ionisation by collision with the atoms of the gas. The electric discharge is then accompanied by a visible glowand, as is well known, the impedance of the tube is very low.

A coldor hot cathode may be used.

It will be appreciated that there is produced by the cathode-anode potential difference an electrostatic field extending from the cathode to the anode longitudinally of the tube and the basic idea underlying the invention is to apply a transverse magnetic field by which the electric current passing/imm the cathod to the anode may be diverted tothe collector electrode. Thus it is an object of the invention to provide a method of converting direct current into altervnating current.

Another object oi the invention is to provide a method of converting alternating current of one frequency into an alternating current of another frequency.

Another object of the invention is to provide an electric trigger or relay device which has none of the disadvantages arising from sparking suffered by the known mechanical devices of this type. A Y. Yet another object of the invention is to provide a method of converting direct current into alternating current with the use of a single electric discharge tube instead of, as in the known methods, two such discharge devices.

Other objects and advantages of the invention will become apparent from the following description of the best known lmethods of carrying outv the invention whichwill be described with reference to the accompanying drawings, in which:

Figure 1 illustrates a method of converting an alternating current of one frequency to an alternating current of another frequency; l

Figure 2 illustrates an alternative method of producing the same result; Figure 3 illustrates a method of converting direct current to alternating current;

Referring now to Figure l, the tube used cornprises an evacuated glass envelope I0 filled with an inert gas to a pressure of the order of one millimetre of mercury. Within it are disposed a cold cathode I I, a cylindrical collecting electrode I2 and a disc anode I3. An alternating potential diiference is applied in any known or suitable manner across the cathode-anode. Forv example, the alternating H. T. may be derived from an induction coil one end of the primary of which is grounded. Externally of the tube is a permanent horseshoe magnet -I4 which, when brought near the discharge path between the cathode and anode causes a current to flow through an external load circuit I5 connected with the collector I2.

By varying the position and/or strength of the permanent magnet I4,' there can be produced in the load circuit either an intermittent direct current or an alternating current, the frequency of the latter being dependent upon the strength of the transverse magnetic field produced.

A somewhat similar arrangement is illustrated in Figure 2. The tube used is similar to that shown in Figure 1 except that a hot cathode I6 is used. A magnetic field transverse of the eleci trostatic field is? in this case produced by an electro-magnet Il the strength of which iield may be controlled with the aid of a variable resistance I8, the current for the electro-magnet being supplied from battery I9.

An alternating potential'diiference is applied across the anode-cathode, and by varying the strength of the ymagnetic eld alternating currents ci'l a wide range of frequency can be produced in the external load circuit i5.

iy applying a steady .direct current or an interrupted direct potential difference across the anode-cathode there is produced in the load cir- "cuit an alternating current superimposed upon a direct current.

In Figure 3 there is illustrated an arrangement which is self-exciting for converting direct current into alternating current. Withinl the tube 20 is arranged a heating filament 2l, a cathode 22, a collecting electrode 23 and an anode 24.

Current passing to the anode traverses the coils of an electro-magnet 25, thence to wrst' primary coil 2'6 to the positive terminal of a source of direct current, the negative terminal of which is connected with the cathode 22.

When the tube is switched on current passes from the cathode to the anode and the electrorent and in the second primary 2l the negative' half-cycles of roughly the same alternating frequency. Hence, in the secondary 28 there is produced a full alternating current.

' In Figure 4 there is illustrated an arrangement similar to that of Figure 3 except that'the two sets of half-cycles produced in the anode and collector circuits respectively are kept separate andby means of the transformers 29 and 3G are used to produce two alternating currents.

In Figure is illustrated an arrangement similar to that of Figure 4 but in which the direct high potential diierence applied across the cathode-anode is produced with the aid of a motor generator. In order to assist in the smooth running of the motor generator, and to avoid dainage which might otherwise occur at breaks of the anode circuit, the motor Vgenerator 3l is shunted by a floating battery 32 in series withla variable resistance 33.

In Figure 6`is illustrated a self-excited parallel type of vcircuit for converting direct current to alternating current. In this circuit, if small alternating voltages are applied to the collector electrodes 34 and 35 inv opposite phases, current from the direct current source is ldiverted alternately through the two lprimary windings 36 and 31 respectively Vof the transformer 38 and, consequently, alternating current is Ainduced into the secondary 39. A small independent source of alternating current could be used to energise the collectors 34 and 35 and to control the frequency of the output but preferably a part of the altery nating current output is fed lback to energise the collectors and thus to make the arrangement self-exciting. The frequency of operation may be controlled by adjustment of the values ofthe condenser 40 and the resistance 4I, whilstl the condenser 42 ensures that the phase of the collector voltage waves is in correct: relationship with that of the anodes.

It will be seen that V this arrangement operates upon the same principles as those of Figures 3,

' 4 and 5. lWhen current flows to the anodes 43 and 44 the electro-magnetic coils 45 and 46 arev energised and the tube current is diverted 4to the collectors 34 and 35, thus stopping the anode currents, whereupon the coils 45 and 46 are deenergised and the anode currents 4start again.'

It maybe preferable, insteadvof allowing thecharges collecting on the electrodes 34 and 35 to leak away through the condenser 40, to vallow these charges to leak away to earth through suitable condensers, in which case the electrodes 34 and 35 should each be connected to earth through a condenser.

In Figure 'z is illustrated methods of control-- ling the strengths of direct currents.

As shown in Figure '7, the tube comprises an indirectly heated cathode 4l, a collector electrode 48 and an anode 49. When a potential diierence is applied across the cathode-anode a comparatively large current` flows to the anode and a small current to the collector electrode, which latter electrodeis connected to earth through a load resistance `5|l, a load resistance 5l also being inserted in the anode circuit. By increasing the strength of -an electro-magnet 52 the anode current may be decreased and the 'collector current increased. The same eect can, of

course, be produced by keeping `the strength of l the electro-magnet constant and decreasing the ileld which is transverse of the electrostatic eld;

it is not essential that the magnetic eld should be exactly perpendicular to the electrostatic'eld but it should at least be oblique thereto. The strength of the magnetic eld can bevaried by varying the position of a magnet or the strength of an exciting current of an electro-magnet.

In all of the devices which havebeen described above for the production of alternating current from a direct current'it will be appreciated that if the direct potential diierence applied across the anode-cathode changes, for example decreases, the current passing through the electromagnet also decreases, so that the eiect upon the alternating current generated is to decrease its amplitude without substantially aiecting its frequency. This is an advantage which is not possessed by the mechanical type of converter.`

I claim: 4

1. A method of modifying an electric lcurrent, wherein a potential difference corresponding with the current is applied across the cathode-anode of an ionic discharge tube to produce between the said electrodes an electrostatic eld and hence an electric current, modification of the latter current being achieved by applying a magnetic field transversely ofthe electrostatic field to cause at least a portion of the anode current to be diverted to a collector electrode disposed between the anode 'and cathode, the desiredmodified current being produced in an external circuit'associated with the said collector electrode.

2. A method as claimed in claim 1, wherein an intermittent direct potential diierenceis applied across the anode-cathode of the ionic discharge tube in order to produce an alternating current in the collector circuit.

3. A method asclaimed in claim 1, wherein an alternating potential diierence is applied across the anode-cathode in order to produce an alternating current in the collector circuit, the frestrength of the transverse magnetic neld.

l4. A method as claimed inclairn l, wherein a direct potential difference is applied a'cross the l anode-cathode in order to produce an alternating current in the collector circuit, the frequency and amplitude of which alternating currentls controlled by varying the strength of the transverse magnetic field'.

5. A method as claimed in rclaim 1, wherein a direct potential difference is applied across the anode-cathode, and the anode current is passed through the coils of an electro-magnet used to diverttthe electric discharge to the collector electrode.

6. A method as claimed in claim 1, wherein a direct potential difference is applied across the anode-cathode, and the anode current is passed through the coils of an electro-magnet used to divert the electric discharge to the collector electrode, the system being'self-exciting and the lnterrupted currents produced in the anode and collector circuits respectively being used to induce an alternating current in a circuit associated with said anode and collector circuits.

7. A method as claimed-in claim l, wherein a direct potential difference is applied across the anode-cathode, and the anode current is passed through the coils of an electro-magnet used to divert the electric discharge to the collector electrode, the system being self-exciting and the in-A termittent currents developed in the anode and collector circuits respectively being used to lnduce alternating currents in separate circuits associated with the anode and collector circuits respectively.

8. A method as claimed in claim 1 for convert'- ing direct current into alternating current,

across the anode-cathode paths of a paix' of ionic discharge tubes connected in parallel so as to -wherein a direct potential dierence is applied produce between each anode and cathode an electrostatic field and hence an electric discharge, intermittent transverse magnetic elds which are 180 out of phase with respect to each other being applied to the tubes in order to produce intermittent anodecurrents which are used to induce an alternating current in a circuit associated with said anode circuits.

9. A method as claimed in claim l, for converting direct current into alternating current, wherein a direct potential difference is applied across the anode-'cathode paths of a pair of ionic discharge tubes connected in parallel s'o as to produce between each anode and cathode an electrostatic field and hence an electric discharge, intermittent transverse magnetic iields which are 180 out of phase with respect to each other being applied to the tubes in order to produce in termittent anode currents which are used to induce an alternating current in a circuit associated with said anode circuits, the intermittent transverse magnetic fields applied to the electric discharge within the tubes being produced by electro-magnets energised by currents derived from the anode currents.

10. A method as claimed in claim 1 for controlling the strength of a direct current wherein a direct potential difference is applied-across the cathode-anode of the ionic discharge tube and a transverse magnetic field is applied to control the strength of the current generated in the collector circuit.

ADOLF PERELMANN. 

